The key factor that will determine the speed and depth to which multi-agent systems penetrate the commercial marketplace is the ease with which applications can be developed. One approach is to use general purpose languages to construct layers of agent level constructs. Object-oriented languages have been advocated as appropriate for the complexity of distributed systems. According to Gasser and Brim , the key problem with the common forms of object based concurrent programming is the fixed boundaries they give to agents are too inflexible. They do not reflect either the theoretical positions emerging in Multi-agent systems, MAS, nor the reality of multilevel aggregations of actions and knowledge. This paper advocates the use of a rather different type of object based concurrent language, stream logic programming, SIP, that does not have this drawback.